Hello everyone.
I can’t trust my homeassistant install (pi + sdcard) because it’s corrupted every time i lose power even with a ups (switching time), i decided to connect a sonoff device to the diybms controller board relay.
First i started with the RE5V1C that is a 5v device, connected the push button to the relay using the pulse fonction.
The wire to the push button is not easy to solder and no way to keep the status on or off, just pulses and if you miss one pulse it won’t work as you want.
Now with a Mini R2 i am able to have a real on/off status following the bms relay switch (don’t forget to activate the follow mode in the options).
The sonoff external switch is connected to the diybms relay.
The device starts working at 18vdc, but i modified mine to work of 5v.
For that i removed all the 220v components and connected the exterior screw connector to the 5v input of the voltage regulator.
Now you can control your water heater or car charger in the house with automations, and have the bms in the shed far far away…